Hi Chris,
This has nothing to do with TraditionalForm, but more with automatic
simplification. If you enter TraditionalForm[
Exp[I \[Theta]] == Cos[\[Theta]] + I Sin[\[Theta]] // ComplexExpand]
you get True in the first case as well.
If you want to show the second equation in traditional form you could
use TraditionalForm[Cos[x] == Sin[x + \[Pi]/2] // HoldForm]
or just write it in a text cell and then use the menu Cell/Convert to/
Traditional form.
Cheers -- Sjoerd
On May 7, 12:39 pm, uk.org.micros... at googlemail.com wrote:
> Hi
>
> The Mathematica 7 documentation says that
>
> TraditionalForm[Exp[I \[Theta]] == Cos[\[Theta]] + I Sin[\[Theta]]]
>
> will display the expression in traditional form, and indeed it does.
> However, the following evaluates the expression and then displays True
> in traditional form:
>
> TraditionalForm[Cos[x] == Sin[x + \[Pi]/2]]
>
> Why is TraditionalForm behaving differently in these two apparently
> identical situations, and how can I get Mathematica to display this
> trigonometric identity in traditional form?
>
> Thanks in advance
>
> Chris